The present invention relates to ovens that are suitable for cooking food products, such as for baking dough products, and methods of cooking such food products where such ovens utilize heat convection at least in part in the cooking process, such as by forced heated gas that is directed to impinge upon the food product. In particular, the present invention is directed to such an oven apparatus and methods of cooking where steam is introduced within the convective heat transfer mechanism for imparting a desired cooking characteristic, such as in the case of a dough product a desired surface texture or sheen.
Conventional dough products are cooked or baked in many different ways depending on the desired organoleptic characteristics that are desired for a particular dough product. Dough products, as used throughout this Application, means any food product that utilizes any formulation of a dough at least in part in making up the food product. Characteristics of the dough which may be attained based at least in part on the cooking technique include texture and sheen attributes of the dough surface or crust. Baking techniques, such as temperature, time and the heat transfer mechanism that is used, can also be at least partially responsible for characteristics of the dough product beneath its surface or crust, such as related to the cooked dough product density and texture. As examples, the cooked dough product may be dense and chewy or light and airy. These characteristics, of course, are also dependent on other dough features, such as the dough formulation.
The present invention was developed in particular for the baking of dough products that have a dense, chewy texture, and an exterior surface sheen. Examples of such dough products include bagels, soft pretzels, French bread, rye bread, sticky buns and the like. Such products may optionally comprise a filled dough product or be mixed or otherwise combined with other ingredients. The dough that is typically used to make such dough products generally includes flour, water and a leavening agent, preferably an active yeast culture. The dough may also include other optional ingredients, for example, sweeteners, flavorings, and fat products. The dough products can be filled with a variety of fillings, and such fillings are preferably substantially retained within the dough crust after processing.
Bagel products are characterized as having a dense, chewy texture and having an exterior sheen. As used throughout this application, a bagel product is meant to include all types of bagels and other products that incorporate or use similar dough and which similar texture and sheen characteristics are desired. Moreover, bagel products may include filled bagel products.
Traditionally, bagel products are prepared by simmering them in boiling water prior to baking. In particular, bagels are typically boiled for between and 30 and 120 seconds on each side thereof prior to baking. After boiling, the bagels may be permitted to drain for a short period followed by a baking cycle that conventionally comprises baking at 400xc2x0 F. for about 25 minutes. During the boiling step, the bagel is believed to expand to its ultimate desired geometry. Then, upon baking, excess surface moisture is driven off and the crust setting takes place. No significant expansion is believed to occur during the baking step. Thus, the desired product geometry, flavor and texture is achieved.
As an alternative method of making bagel products, steam baking has been utilized to provide a similar result. In steam baking, a baking chamber is saturated with moist air or steam so that the surface of the bagel product is exposed to sufficient water for enough time to permit the dough to expand to its desired geometry and after which the crust can set. In other words, steam injection provides sufficient water to keep the bagel product in a moist environment for delaying the setting of the outer structure of the bagel product so that it can expand sufficiently before forming an outer shell. Such cooking also results in the desired texture and sheen attributes associated with such bagel products.
For example, a conventional rack oven can be provided with steam injection through associated steam coils. A suitable rack oven can be obtained, for example, from Gemini Bakery Equipment Company of Philadelphia, Pa. In such conventional baking chambers, sufficient moisture (i.e., steam) must be provided to fill the entire baking chamber to ensure that the desired moisture quantity is provided around the bagel product during cooking. In particular, that means that the entire oven baking chamber should be filled with an air/steam mixture to the saturation level of the steam. This technique, although effective, requires a high usage of steam (because the entire baking chamber is filled) thereby requiring a relatively large steam generation capacity. Furthermore, saturating the entire internal baking chamber of an oven with steam can very detrimentally affect the oven, particularly over the long term.
Yet another alternative for making bagel products is disclosed in U.S. Pat. No. 5,965,180 to Lonergan, which is commonly assigned to the assignee of the present invention and the disclosure of which is entirely incorporated herein by reference. Disclosed in the Lonergan patent are certain glazes that have been developed for the purpose of mimicking the effect of boiling or steam baking. The glazes are designed to maintain excess water on the bagel products surface for long enough to permit the dough to expand to its desired geometry prior to the crust setting and to make the desired chewy texture. With such glazes, the boiling step can be eliminated. By baking the bagel products with an applied glaze under otherwise normal baking conditions and in a conventional oven, certain desirable bagel characteristics can be attained. Such process, however, requires the time and cost requirements of the ingredients in making such a glaze and applying such a glaze to the product dough prior to being cooked.
Dough products other than the bagel products discussed above are known to be cooked in such conventional ovens without the provision of any steam at all. That is, many dough products are cooked without the presence of moisture or steam because they do not intend to have the texture and sheen attributes associated with bagel-like products. All sorts of conventional ovens (both commercial and household types) have been developed including a wide variety of different types of baking chambers that are suitable and adjustable for a very wide variety of dough products.
One specific type of oven that has been developed for commercial use has found acceptance in baking other dough products where speed of the baking is desired while maintaining other specific baking characteristics. Gas impingement baking ovens have been developed that rely on a convective heat transfer mechanism for quickly and accurately cooking dough products as they pass through the oven on a conveyor. Specifically, a typical impingement oven utilizes high velocity, low mass hot gas is directed at the food product through nozzles. This heated gas may be directed to impinge the food product from one or both sides thereof. If directed from both sides, the conveyor permits the gas to pass to impinge on the supported side of the food product. Columnar gas streams or jets are provided for impinge in one or both sides of the food product during the baking process. Nozzles or fingers having an array of nozzle orifices that extend over and/or under the food product transfer conveyor are utilized for providing a dispersed heated gas supply mechanism. The baking chamber""s thereof may additionally be heated by other means, but preferably, the food product cooking is primarily accomplished by convective heat transfer from the heated gas columns or streams. Impingement ovens can be obtained, for example, from APV Baker Inc. of Grand Rapids, Mich., under the trade names xe2x80x9cJet Sweepxe2x80x9d or xe2x80x9cEnerjet.xe2x80x9d
In certain baking situations, it has been found useful to provide steam within the baking chamber of such impingement ovens to increase the moisture about a food product during its baking process. That is, a steam supply can be connected to provide steam within the baking chamber so as to provide a moist environment around the food products during baking, which baking is still primarily accomplished by the convective heat transfer of the gas columns or streams. However, achieving high levels of steam presence is particularly difficult within the baking chambers of such impingement ovens. As described above, high steam level presence (preferably to the level of saturation) is needed to achieve the preferable characteristics of bagel products. First of all, the baking chambers are relatively large because they cook food products as they are conveyed through the ovens and the baking chamber substantially extends the entire length that the food products are conveyed through the impingement oven. Thus, a large steam generation capacity is required. As above, exposing the internal oven mechanisms to high levels of moisture is generally not good for the oven mechanisms over time. Furthermore, the nature of impingement oven tends to force steam away from the food products during cooking. That is, the food products are affected mostly by the heated gas that is impinged thereon.
The present invention overcomes the deficiencies and shortcomings of the prior art by providing techniques for creating an effective moisture environment around a food product during baking while the food product is baked in an oven that cooks the food product at least in part by a convective heat transfer mechanism. In particular, the present invention provides the ability to bake bagel products by a convective heat transfer oven within an effective moisture environment for creating desired surface sheen and texture characteristics.
An oven in accordance with a present invention utilizes a convective heat transfer mechanism for cooking the food products. Preferably, the oven comprises an impingement oven that utilizes heated gas provided in the form of columns or streams and which are directed to at least one surface of a food product within the oven. By the present invention, moisture, in the form of steam, is introduced within the convective heat transfer mechanism. Thus, an effective moisture environment can be created at and around the surface of the food product that is cooked under the influence of the heated gas/steam columns or streams. More preferably, steam is introduced within the convective heat transfer mechanism for creating a moisture environment substantially surrounding the entire food product during its baking.
Such an oven is advantageous in that food products, in particular dough products, and even more particular bagel products, can be baked by a convective heat transfer mechanism that provides for quicker and more even cooking of the food product while providing for the making of whatever level of moisture is desired about at least part of the food product for imparting a desirable characteristic to the food product. In the case of dough products, moisture may be desirable for any number of reasons during the baking step. With bagel products, as detailed above in the Background section of the subject application, bagel product surface sheen and texture can be achieved by providing an effective moisture environment that mimics a saturated steam environment of a conventional oven chamber. This permits the dough expansion that is desired to create the desired bagel product geometry and thereafter the baking of the dough beneath the surface or crust to create the chewy nature of the dough.
The present invention is also directed to methods of cooking food products, in particular dough products, and even more particular bagel products. Such methods primarily conduct baking by providing a convective heat transfer to the food product. In accordance with present invention, moisture is introduced within the convective heat transfer mechanism during the convective heating step. Thereby, an effective moisture environment is created about at least a portion of the food product during its baking so that a characteristic of the food product can be achieved that is associated with the provision of an effective level of moisture at a surface of the food product. In the case of a bagel product, desirable bagel product surface sheen and texture can be achieved and the bagel dough can thereafter be cooked as also desired to create its chewy nature.
Moisture is preferably introduced as steam within the heated gas of the convective heat transfer mechanism. The heated gas may comprise air or any other carrier gas capable of heat transfer and carrying moisture. More preferably, the steam is introduced within the heated gas prior to it being ejected from its supply nozzle that is used to create the heated gas jets or streams for impinging on the food product. Thus, by creating an effective steam environment, preferably as high as the level of saturation for bagel products, with the heated gas prior to its ejection, an environment having a high water to gas ratio with highly saturated conditions can be focused at the food product surface. The particular advantage is that the steam is focused at the food product surface so that moisture at the food product surface can be maximized while the steam levels within the overall baking chamber can be minimized. The high water to gas ratio environment can be substantially provided at and about the food product without having to create a highly saturated environment within the entire baking chamber. Appropriate conditions with respect to temperature and moisture are created in the micro-environment of higher humidity near the product surface. Otherwise, the baking chamber need not experience highly saturated conditions throughout. This, of course, is better for the oven mechanisms in the long-term and permits the high throughput and reduced baking dwell time advantages of impingement baking to be achieved while making a food product that advantageously achieves desired moisture related characteristics. Additionally, steam usage is minimized.
By delivering the steam and creating the high water to gas ratio environment near the product surface, there is no need to create a homogeneous environment of high humidity within the entire baking chamber. It is also possible to selectively provide the steam to the nozzles of the impingement oven. This creates greater flexibility to the oven design. For example, with a bagel product, steam may be introduced within the nozzles of the initial cooking segment of the oven to achieve desired results early on in the baking cycle, while other baking zones, such as downstream of an initial section, can be otherwise controlled. This is advantageously permitted in that high humidity zones are merely created in the micro-environment about a food product in only the desired zone or zones of one or more stages of an impingement oven. With greater flexibility in designing the impingement oven, greater flexibility in terms of generating food products with varied attributes, such as crust texture and surface sheen, can be achieved.
The aforementioned advantages of the present invention are achieved by an apparatus for heating and cooking food products that utilizes convective heat transfer as a manner of providing heat to the food product, where the apparatus includes an oven chamber within which a food product can be positioned for heating thereof, a supply nozzle for connection to a heated gas supply, the supply nozzle including a receiving chamber within which heated gas can enter from the heated gas supply and at least one fluid directional opening from which heated gas can be ejected toward a food product that is supported in position within the oven chamber, and a steam injector connectable to a steam supply, the steam injector including at least one opening that is positioned relative to the receiving chamber of the supply nozzle so that steam can be injected into the receiving chamber of the supply nozzle. As a result, heated gas and steam can be provided at the same time to the receiving chamber of the supply nozzle so that the heated gas and steam can mix together prior to being ejected from the fluid directional opening of the supply nozzle toward the food product and the heated gas and steam mixture can be utilized for convective heat transfer for heating the food product.
Preferably, the supply nozzle is an impingement nozzle that has a plurality of fluid directional openings so that heated gas and steam can be ejected toward the food product while steam is injected into the impingement nozzle by a steam nozzle that extends therein. Many different types of arrangements are contemplated utilizing plural impingement nozzles, some or all of which may have steam injection. Moreover, oven sections, modules and cooking zones are contemplated that may be arranged in any number of ways for heating a food product according to any particular application. Also, a steam distribution system is preferably provided that is connectable to a steam supply and that interconnects with the steam nozzles of the oven chambers.
The aforementioned advantages the present invention are also achieved by a method of heating a food product by convective heat transfer comprising the steps of supporting a food product within an oven chamber, and heating the food product by convective heat transfer within a moisture environment by impinging at least a portion of the food product by a fluid stream that is directed at the food product by an impingement nozzle, the fluid stream comprising a heated gas and steam mixture. The method preferably further includes the steps of supplying heated gas to a receiving chamber of the impingement nozzle, and injecting steam from a steam injector into the receiving chamber of the impingement nozzle while the heated gas is supplied to the receiving chamber of the supply nozzle so as to provide the heated gas and steam mixture. The method of the present invention is particularly suitable as a method of cooking a dough product, and more particularly to a method of cooking a bagel product.